The invention relates to a method and a device for adjusting a quantity of ink supplied to an impression cylinder of a printing machine.
Quality demands on printed documents continue to increase, so that precise control of a printing machine for applying ink to a printing material is necessary.
Printing machines are operated at different printing speeds, depending upon the print job, so that the rotational speed of the impression cylinder changes, which has a corresponding influence upon the quantity of ink supplied to the impression cylinder.
German Patent (DE) 24 45 908 discloses an inking unit and a density regulating device for printing machines in which a precise amount of ink is applied to the printing material. Flexible measuring elements similar to plates are used for this purpose. By using zonal measuring elements, it is possible to adjust the ink flow to an appropriate value. The resulting properties of the measuring elements permit the amount of ink applied to a transfer roller and, therefore, to the printing material, to be varied during corresponding changes in the speed of movement of the printing material. In this regard, the quantity of ink supplied to the impression cylinder is regulated as a function of the printing speed.
A disadvantage of this heretoforeknown method is that, for each speed change, the individual ink setting elements have to be moved. In addition, it has become known heretofore to perform speed compensation by adjusting the length of the ink stripe.
It is accordingly an object of the invention to provide a method and device for regulating a quantity of ink supplied to an impression cylinder by which an improved regulation of the ink quantity is possible.
With the foregoing and other objects of the invention, there is provided in accordance with one aspect of the invention, a method of adjusting a quantity of ink supplied to a printing material by a printing machine, which comprises adjusting the quantity of ink as a function of the printing speed, and including, upon the occurrence of a change in the printing speed, making a change in the quantity of ink as a function of area coverage to be printed.
In accordance with another mode, the method of the invention includes changing the ink stripe length for adjusting a requisite quantity of ink.
In accordance with a further mode, the method of the invention includes storing characteristics for the ink stripe length for various area coverages as a function of the printing speed and, upon the occurrence of a change in the printing speed, varying the ink stripe length in accordance with a respective characteristic.
In accordance with an added mode, the method of the invention includes changing the quantity of ink by changing an inking zone level, the inking zone level representing the thickness of the ink with which the ink is applied to a ductor roller.
In accordance with an additional mode, the method of the invention includes differently adjusting the inking zone level for inking zones, and using a prescribed area coverage of one inking zone for controlling the quantity of ink for the inking zone.
In accordance with a concomitant aspect of the invention, there is provided a device for printing a printing material, comprising an ink duct having an ink duct roller, a pivotable ductor roller and a transfer roller, the ductor roller being bringable into contact both with the ink duct roller and the transfer roller, the transfer roller serving for transferring a quantity of ink transferrable from the ductor roller to the printing material via further rollers, a control device for adjusting a contact length of the ductor roller on the ink duct roller as a function of printing speed, the control device being connected to a memory having stored therein values for an ink stripe length as a function of the printing speed and an area coverage to be printed, the control device serving for adjusting the ink stripe length as a function of the printing speed and the area coverage.
A significant advantage of the invention is that the amount of ink to be supplied to the printing cylinder is adjusted as a function of an area coverage to be printed.
The quantity of ink is preferably adjusted over the length of the ink stripe.
In a further embodiment, the quantity of ink is adjusted by adjusting the inking zone level.
The ink level can preferably be adjusted individually for each inking zone.
In addition, it is advantageous to adjust the quantity of ink over the length of the ink stripe and the inking zone level.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as a method and a device for adjusting a quantity of ink supplied to an impression cylinder of a printing machine, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, wherein: